This picks up on Bernard's point regarding Sets in RM. I appreciate that
RM does not subscribe to any mathematical set model but i wonder about
when do individuals become sets?
I'm not sure I found it but if I have two assertions in different maps where:
graham worksfor empolis gmbh
graham worksfor empolis uk
and I merge them what happens?
is it now true that
graham worksfor [empolis gmbh, empolis uk]
through merging, or are the two assertions seperate?

Exact. But if the role player x is not a set, how do
you make distinct the subject x and the set {x}? The second one is also a
subject, which is exactly the set of subjects that play the role ... So
you have a problem here, and the only consistent way I see to solve it is
to say: "a role player is always a set of subjects".

No grouping semantics of any kind are defined by this RM4TM. This
RM4TM requires all groups to be explicitly represented as nodes. Any
other approach would open the possibility for knowledge about a group to
fail to be connected to the single node whose subject is the group, and
that would be contrary to the Subject Location Uniqueness Objective.